Water softening and washing product and method of preparing same



Patented Oct. 2, 1945 UNITED .STATES- PATENT" OFFICE WATER SOF'IENING AND WASHIN G PROD- UCT AND LIETHOD OFPREPARING SAME Leonard Meites, Chicago, 111. No Drawing. Application March is, "1942,

Serial No. 434,478

Claims. (01. 252-135) pared by reacting monosodium dihydrogen phosphate with a trialkali metal orthophosphate, particularly trisodium orthophosphate, at elevated temperatures but below the fusion point of the reaction mixture and also below the temperature of disintegration of the desired reaction product,

the molal ratio of the trialkali metal orthophosphate to the monosodiumdihydrogen phosphate being between approximately one to two and two to two. In the preparation of my novel reaction products, I have found it particularly advantageous to utilize crystalline trisodium phosphate containing twelve molecules ofwater of crystallization (NasPOalZI-IzO) and, where reference is red heat, and ranges to that approaching a bright red heat. In terms of temperature values, a satisfactory range is from approximately 300 degrees C. to approximately 525 degrees 6., although the temperature may vary somewhat from these values. If the reaction mixture is heated at' or above that temperature which I characterize as the temperature 'of disintegration of the desired reaction product, thedesiredreaction product apferred embodiment, tetrasodium made to molal ratios, it will be understood that I utilize the numerical value of 380 as the molecular weight of the crystalline trisodium phosphate. I also prefer, particularly, to employ monosodium dihydrogen phosphate containing one molecule of water of crystallization (NaHaPOaHzO) and, where reference is made to molal ratios, it will be understood that I utilize the numerical value of 138 as themolecular weight of the monosodium dihydrogen phosphate. Where different products are utilized,'for example, anhydrous monosodium dihydrogen phosphate or monoso'dium dihydro en phosphate containing two molecules of water of crystallization, an adjustment should be made in determining the molal ratios.v

The exact structure of my novel alkali metal phosphate products has not yet been fully ascertained and, therefore, I deem it best and most accurate to characterize my novel products as re-" action products of the defined reactants produced by heating under stated temperature conditions.

As I have pointed out hereinabove, the reaction mixture should not beheated to a tempera".

ture sumciently high to fuse the reaction mixture nor, as I have stated, should it be heated .to a temperature sumcientlyhigh to eifect disintegration of the desired reaction product. The temperature at which the reaction best proceeds, generally speaking, is that corresponding to a dull 276 parts by weight of monosodium dihydroge'n spirit of my invention.

pears to break 'down into what evidently comprises tetra-alkali metal pyrophosphate and alkali metal metaphosphate, or, in my particularly prepyr ph sphate and sodium metaphosphate; 1

In order that those skilled in the art may more fully understand the manner, in which my novel reaction products are produced, I set forth herein below representative examples which, it will be understood, are illustrative and are in nowise tov be construed as limitative of the full scope of my invention. Thus, for example, the proportions of the reactants may be varied, diflerent trialkali metalorthophosphates and monoalkali metal dihydrogen phosphates may be utilized, and the temperatures'and times of reaction may be varied, within limitatitons, without departing from the E ma-1 380 parts by weight of crystalline ,trisodium phosphate mazroiizmo) and 276 parts by weight of powdered monosodium dihydrogen phosphate (NaHzPoaHzo) were mixed together and heated todryness at a temperature of ap-' proximately 400 degrees 0:450 degrees for a period of one-half hour with periodic mixing, The resulting reaction product was then Permitted to cool. It comprised-a readilywater-soluble, white crumbly or powdered material having exceptional properties as awater-softening agent.

Example;

760 parts by weight or crystallinetrisodium phosphate (NaaPOalZHaO) were admixed with phosphate (NaHzPOaHaO) and the reaction mixture was heated, with periodic stirring or mixing, at a temperature ranging from 350 degrees 0,-450 degrees C. for a period of about one hour. The

resultingv reaction product .was a readily watersoluble white crumbly or powdered material which had exceptionally satisfactory properties as ,a

water-softening agent and for 7 other purposes'as hereinafter disclosed. 7 u

. Example ,3 570 parts by weight of crystalline trisodium phosphate (NaaPO4.12I-I2O) were admixed with 276 parts by weight of monosodium dihydrogen phosphate (NaHsPO.I-Iz0) and the reaction mixture was heated with periodic stirring'or mixing, at a temperature ranging from 400 degrees C.-450 degrees C. for a period of about one hour. The resulting reaction product had properties similar to those of Examples 1 and 2.

A very satisfactory and convenient test to ascertain when the reaction between the trisodium phosphate and the monosodium dihydrogen phosphate is completed is to make up an aqueous solution of the reaction product and add it to a dilute aqueousisolution of silver nitrate. If the reaction product is-not finished, ayellow or yellowish precipitate forms. If, however, a white precipitate forms, the reaction product'may be considered to be finished and satisfactory.

In those cases where the crystalline trisodium phosphate employed contains free caustic soda I or sodium carbonate, which is usually the case with the ordinary commercial trlsodiurn phosphate products, I have-found it advantageous initially to neutralize or substantially neutralize the said free caustic soda or sodium carbonate,

' as the case may be, with an inorganic acid, particularly orthosphosphoric acid, before reacting the crystalline trisodium phosphate with the monosodium dihydrogen phosphate. Alternatively, although not so satisfactorily; I may utilize sufiicient monosodium dihydrogen phosphate in excess of that of the desired molal ratios to effect the neutralization. On the other hand,

where the crystalline trisodium phosphate uti-' lized contains 7 free disodiummonohydrogenorthophosphate (Naz'HPOO I find it advantageous, initially, to admix the said crystalline trisodium phosphate with an alkali, preferably caustic soda, to convert the disodium monohydrogen orthophosphate into. trisodium phosphate, or, al-

, ternative, and more particularly satisfactorily,-

with phosphoric acid to convert the disodium hydrogen phosphate before the reaction with the monosodium dihydrogenphosphate. Instead of preliminarily neutralizing the caustic soda or sodium carbonate or the like with phosphoric acid, the amount of phosphoric acid required may first be ascertained and it, together with the trisodium phosphate and the monosodium dihydrogen phosphate, may be admixed together andheated to the reaction temperature. Where I refer in the claims to preliminary neutralization of the caustic soda-or the like in'the trisodium phosphate, it will be understood to cover this and other alternative methods.

My novel reaction products maybe used for: the

treatment of water and for washingpurposes, for the sequestering of calcium and magnesium, Y as-deflocculating agents, and for various uses in v the textile and other industries and under generally similar conditions to those where heretofore known phosphate or polyphosphate compounds have 'been employed, as, for example, inv

the case of the alkali metal metaphosphates as disclosed in Reissue Patent No.- 19,719 and in the be placed, such uses and the manner thereof being, in the main, disclosed in such patents as those mentioned hereinabove as well as other patents as, for example, Patents Nos. 2,149,734; Re-

"issue No. 20,754; 2,092,913 2,086,867 and the like My novel reaction productsare, however, sharply distinguishable from heretofore known phosphates such as those disclosed in the aforementioned patents not only in their structure but also with respect to various of their properties.

10 Thus, for example, whereas'sodium hexametaphosphate, disclosed in Reissue Patent lid-19,719, has a slightly acid reaction and the sodium tetraphosphate of Patent No. 2,059,570 has a pH of approximately 8.5,

a pH of approximatelys or 9.5 to approximately 10, although the exact pH will vary somewhat depending upon the. exact molecular ratios 0! the reactingconstituents employedand the exact temperature conditions under which they are reacted. in 'view of the pH .values which my novel reaction products possess, they may;par-

ticularly advantageously be utilized-in environj ments or compositions containing various saponaceous materials, especially the higher fatty acid soaps, their alkalinity being generally similar to that of soap solutions. The sudsing of soaps and the stability and volume of foam. are dis: tinctly, improved by the use of my novel ines-- 3 phate reaction products. ilence, forexample,

they readily lend themselves to the preparation of washing compositions containing alkaline sub- .stancessuch as tetrasodlum pyrophosphate, sodi- I um carbonate, and the like as well as sapona- :25 ceous ingredients such as the usual fattyacid soaps, typical compositions'containing from 10% to 60% of my novel reaction productdbalance, for example, soap. It will be understood, in this.

connection, that such compositions maycontain -10 other-alkaline materials and/or diluentsor the like to-provide, dry or powder compositions for distribution and sale for household purposes as well. as, of course, for industrial usage.

Further evidence of the different character monohydmgen phosphate mtg, monosodmm db I of my novel reaction products as compared with known phosphates or polyphosphates may be noted with respect to their behavior with aqueous solutions of different chemicals. Illustrative of these is the behavior when solutions of my lio'novel reaction products are added to aqueous solutions of zinc acetate.- In the case otmy the zinc acetate solunovel reaction products, tion remains clear for a substantial period of time, whereas, aqueous .solutions of sodium hexametaphosphate or sodium tetraphosphate, for exampm, when added to dilute aqueous solutions of zinc acetate, form precipitates in period of time. Even when precipitates, are formed, after the lapse of a substantial period of so time, when my novel reactionproductsare utilized', such precipitates have a different character and appearance from, those which result where theaforementionedpriorart phosphates are utilized. 0n the other hand, ,with

reaction products form precipitates substantially immediately, whereas with the hexametaphosphates and tetraphosphatesthe barium chloride Jsolution'remains clear.

In addition to the advantages or and distincmy novel reaction products 1 in like concentrations in aqueous solutions, have a relatively short aqueous soluo5- tions of barium chloride, aqueous solutions 0! my cost of preparation of such heretofore known agents as sodium hexametaphosphate, sodium tetraphosphate, and the like. In this general connection, I may point out that I regard as especialiy outstanding and important those of reaction products which are derived from approximately two mols of crystalline .trisodium phosphate and two mols of monosodium dihydrogen phosphate or, in other words, equi-molai ratios of the reactants. I

Since various embodiments of my invention may be made without departing from the spirit andscope thereof, in the light-oi the guiding principles which I have disclosed herein, it is to be understood that I do not limit myself to the specific embodiments of my invention except as pointed out in the claims.

What I claim as new and desire to protect by Letters Patent of the United states is:

1. The method of preparing a water-soluble compound which comprises heating a mixture of crystalline trisodium phosphate and monosodium dihydrogen phosphate, in apmolal ratio of from approximately one to approximately two mols of crystalline trisodium phosphate to two mols of monosodium dihydrogen phosphate, at a reaction temperature not substantially below 300 degrees C. but below the temperature of disintegration of the desired reaction product for a period 01 time sufici ent to substantially complete the reaction.

2. The method of preparing a water-soluble compound which comprises heating a mixture of crystalline trisodium phosphate and monosodium dihydrogen phosphate, in a molal ratio .of approximately two mols of crystalline trisodium phosphate to two mols of monosodium dihydrodrogen phosphate, at a reaction temperature not. substantially below 300 degrees C. but below the temperature of disintegration of the desired reaction product for a period of time sllflicient to substantially complete the reaction.

,4. The method of preparing 'a water-soluble compound which comprises providing a crystallinetrisodium phosphate in which any free caustic soda or sodium carbonate present therein is substantially neutralized with phosphoric acid,

- admixing the resulting trisodium phosphate with monosodium dihydrogen phosphate in a. molal ratio of approximately oneto approximately two mols of the crystalline trisodium phosphate to two mols of the monosodium dihydrogen phosphate, and heating the resulting mixture at a re- .action temperature not'substantially below 300 degrees C. but below the temperature of disintegration oi the desired reaction product for a period or time sufilcient to substantially complete the reaction. r

5. The method of preparing a water-soluble compound which comprises providing a crystalline trisodium phosphate in which any free caustic soda or sodium carbonate present therein is substantially neutralized'i with phosphoric acid,

admixing the resulting trisodium phosphate with -mately equal molal ratios, and heating the resulting mixture at thetemperatures ranging from 300'degrees C. to 525 degrees C. for a period c! 1 s time sufllcient to substantially complete the re- 5 action.

6. The methodof preparing .a water-soluble compound which comprises providing a mixture of crystalline .trisodium phosphate and monosodium'dihydrogen phosphate in approximately equi-molal ratios, heating the resulting mixture at'temperatures 013 300 degrees .C. to 525 degrees (3., and then cooling and grinding the reaction mixture to produce a finelydivlded product for a period of time sufiicient to substantially-complete the reaction.

, '7. A water-soluble product comprising a reaction product of crystalline trisodium phosphate and monosodium' dihydrogen phosphate, in a molal ratio of, from about one to about two mols of crystalline trisodium' phosphate'to two mols of monosodium dihydrogen phosphate, at a reaction temperature not substantially below 300 degrees 6.- but below the temperature of disintegration of the desired reaction product and for a period '25 of time sufficient to substantially complete-the reaction. I

8. A water-soluble product comprising a reaction product of trisodium phosphate and monosodium dihydrogen' phosphate, in a molal ratio or from about one to about two mols oi trlsodium phosphate to two mols of monosodium dihydrogen phosphate, at temperatures ranging from about 300 degrees C. to about 525 degrees C. and for a period of time suilicient to substantially complete the reaction.

9. A water-soluble product comprising a reaction product. of substantially equi-molal ratios oi crystalline trisodium phosphate and monosodium dihydrogen phosphate, at a reaction tem erature 0 not substantially below 300 degrees C. but below the temperature of disintegration oi the desired reaction product and for 'aperiod of time sumcient to substantially complete the reaction.

10. A water-soluble product having a pH of the order of about 9 to about 10 in aqueous solution and comprising a reaction product of crystalline trisodium phosphate and monosodium dihydrog'en phosphate, in a .molal ratio of from about one to about two mols of crystalllnetrisoso dium phosphate to two mols of monosodium dihydrogen; phosphate, at a reaction temperature not substantially below 300 degrees C. but below the temperature of disintegration of the'desired reaction product and for a period 01 time sumcient to substantially complete the reaction.

11. A water-soluble product comprising a reaction product ofmonosodium dihydrogen phosphate and crystalline trisodium phosphate in which any free caustic soda or sodiumcarbonate present in the trisodium phosphate is substantially neutralized with phosphoric acid, in a molal ratio or approximately one to approximately two mols of the crystalline trisodium phosphate to one mol oI-the monosodium dihydrogen -phos 05 photo, at a reactiontemperature not substantially below 300degrees C. but below the temperature of disintegration oi. the desired reaction product and for a period of time sufliclent to sub- 'stantially complete the reaction.

12. A water-soluble product having a pH of the order of about 9 to about 10 in aqueous solution and comprising a reaction. product of substantialiy equi-molal ratios 01 monosodium dihydrogen phosphate and: crystalline itrisodium phos.

moncsodium dihydrogren phosphate in approxi-'v 16 phate in which any free caustic sodaor sodium taliine trisodium phosphate phosphoric acid,

C. but below, the temperature 0! I aaeuea'o action product and for a I to substantially complete the reaction.

' 15. The method of crystalline trialkali me'tai phosphate and mono- 1 alkali metal dihydrogen phosphate, in a molal ,ratio of from approximately one to approxi mately two mols of crystalline'trialkali metal kaline detergent material and a reaction product Y of crystalline trisodium phosphate and monosodium dihydrogen phosphate, in a molal ratio of ,irom about one to about two mols of crystalline I trisodium phosphate to two mols of monosodium dihydrogen phosphate, t a temperature ranging from approximately 300 degrees C. to approximately 525 degrees C.

' '14. A washing composition comprising a wa-.

and for a period of time suflicient to substantially complete the reaction.

ter-soluble'soap and a reaction productof crys-' and monosodium 1dihydrogen phosphate; in a molal ratio of from about one totwo mols of crystalline trisodium phosphate to two mols of monosodium dihydrogen phosphate, substantially below 300 degrees C. but below the temperature oi disintegration of the desired reat a reaction temperature'not' phosphate and phosphate to dro'genv phosphate, at a reaction temperature not substantially below '300 degrees C. but below the temperature of disintegration o! the desired reaction product for a period or time sufllcient to substantially complete the reaction,

16. A water-soluble product comprising a reaction product of crystalline trialkali metal phosphate, in a molal ratio of from about one to about two mols phosphate to two mols of monoalkali'metal dihydrogen phosphate, at a reaction temperature not substantiallybelow 300 degrees C. but below the temperature of disintegration of the desired reactionproduct. T

' LEONARD MEITES.

period oi time sumcient v preparing a water-soluble compound which comprises heating a mixture of two mols or monoalkali metal dihymonoalkali metal dihydrogen of crystalline trialkali metal 

